GI Hormones & Physiology Flashcards
What do gastric parietal cells produce?
HCl, intrinsic factor
What do chief cells produce?
Pepsinogen
What do G cells produce?
Gastrin
What do mucous neck cells produce?
Bicarbonate mucus
What is pepsin?
Proteolytic enzyme that hydrolyzes peptide bonds
What is intrinsic factor?
Protein secreted by the parietal cells that combines with vitamin B12 and enables absorption in the terminal ileum
What 3 substances stimulate HCl release by parietal cells?
- Histamine
- Acetylcholine
- Gastrin
What is the enterohepatic circulation?
Circulation of bile acids from the liver to the gut and back to the liver via the portal vein
Where are most of the bile acids absorbed?
Terminal ileum
How many times is the entire bile acid pool circulated during a typical meal?
Twice
What are the stimulators of gallbladder emptying?
Cholecystokinin, vagal input
What are the inhibitors of gallbladder emptying?
Somatostatin, sympathetics, vasoactive intestinal peptide (VIP)
What is the source of cholecystokinin?
Duodenal mucosal cells
What stimulates the release of cholecystokinin?
Fat, protein, amino acids, HCl
What inhibits the release of cholecystokinin?
Trypsin, chymotrypsin
What are the actions of cholecystokinin?
- Empties gallbladder
- Opens ampulla of Vater
- Slows gastric emptying
- Stimulates pancreatic acinar cell growth and release of exocrine products
What is the source of secretin?
Duodenal cells (argyrophilic S cells)